On mobile data I get >20Mbps from fast.com, with VPN it's 28, without it's 23. Clearly my VPN is *not* throttling me when I use my Virgin connection.
I don't care about the speed I get from speed sites, the entire point of fast.com is that cheats like Virgin cannot game it - why is it acceptable that I pay for 100Mbps but on REAL LIFE SITES I get <5?
Ookla is a device for ISPs to defend themselves. It does not give useful information about download speeds. I regard VM's approach as cheating, similar to Volkswagen - designing systems around tests, not real life situations.
Now... I have to admit that I found this thing: http://www.speedguide.net/downloads.php and having optimised my computer for faster download speeds, I am getting much better results from TestMy and others. Might be worth a go. Choose appropriate speed and tell it to optimise.